The present invention relates to a fume hood which locally exhausts toxic gases generated in an environment such as a research establishment, plant, or hospital, which is hazardous for workers or products and, more particularly, to a fume hood management system which can acquire data related to the safety of workers.
In chemical experiments, gases or dusts that are hazardous for human bodies are often generated in experimental working processes. One of apparatuses that prevent such hazardous substances from diffusing in a room and prevent contamination of human bodies is a fume hood. Generally, a fume hood has an envelope (enclosure) with a sash door that can be opened/closed vertically or horizontally. Workers of a laboratory can access the enclosure through the sash door.
To prevent workers who are working in the fume hood from being exposed to hazardous gases or dusts, the enclosure is connected to an exhaust apparatus for removing the hazardous substances.
As an exhaust control method for such an airflow control system having fume hoods and exhaust apparatus, a VAV (Variable Air Volume) method is known, which changes the exhaust airflow of the fume hood in accordance with the aperture ratio of the sash. In addition, a UBC (Usage Based Controls (tradename)) method is also known, which detects the presence/absence of workers, increases the exhaust airflow only when workers are present, and decreases the exhaust airflow if no workers are present.
In recent airflow control systems, xe2x80x9cdiversityxe2x80x9d has been introduced as a technique for optimizing the system. The xe2x80x9cdiversityxe2x80x9d is a system design concept based on a statistical value, i.e., a fact that as the simultaneous utilization ratio of fume hoods (the ratio of the number of fume hoods that are being used to the total number of fume hoods) converges to a predetermined value as the number of fume hoods increases.
According to this xe2x80x9cdiversityxe2x80x9d concept, the design maximum exhaust airflow, i.e., the maximum airflow that can be exhausted by the exhaust apparatus can be decreased on the basis of the statistical value. Hence, the energy cost can be effectively reduced while safely operating laboratories.
However, the conventional airflow control systems have no means for measuring the simultaneous utilization ratio during an actual operation. The margin at the time of actual operation with respect to the simultaneous utilization ratio at the design stage cannot be confirmed.
The simultaneous utilization ratio at the time of actual operation changes depending on the facility where the fume hoods are installed. In fact, the simultaneous utilization ratio also changes depending on the scale of the facility and the number of workers. Hence, if the system is designed on the basis of only the statistical simultaneous utilization ratio, it cannot be determined whether the design is appropriate. To ensure sufficient safety, the design margin must be large.
Additionally, the conventional airflow control systems have neither means for measuring the maximum exhaust airflow, i.e., the sum of instantaneous exhaust airflows of the fume hoods nor means for measuring the safety margin, i.e., the difference between the design maximum exhaust airflow and the maximum exhaust airflow. Hence, the degree of safety or the facility allowance cannot be confirmed.
As a consequence, in the conventional airflow control systems, data related to the safety of workers, including the simultaneous utilization ratio at the time of actual operation and the safety margin, cannot be acquired. Hence, it is difficult to evaluate the safety of the system.
It is an object of the present invention to provide a fume hood management system which can acquire data related to the safety of workers.
In order to achieve the above object, according to the present invention, there is provided a fume hood management system comprising collection means for collecting data representing an operation state from a plurality of fume hoods, and a server apparatus which comprises arithmetic means for calculating a simultaneous utilization ratio on the basis of the number of simultaneously used hoods and the total number of fume hoods, the number of simultaneously used hoods being obtained from the data collected by the collection means and representing the number of fume hoods that are being used.